The moults and plumages of the scoters-genus Oidemia

THE _AUK:

A QUARTERLY JOURNAL OF

ORNITHOLOGY.

Vol. XXXI. July, 1914. No. 3

THE MOULTS AND PLUMAGES _OF THE SCOTERS,—

GENUS OIDEMIA.

BY JONATHAN

DWIGHT, JR., M. D.

Plates

XXIV~XXX.

The

Scoters are a groupof sea-ducks best

known when

adult

by

their black

plumage and

bright colored, bulging bills.

They

are widelydistributed during the breeding season in the arctic

and

sub-arctic portions of the Northern

Hemisphere and move

south-

ward

in the winter totemperate latitudeswhere theyarefound in greatnumbers. Three species, nigrajusca,

and

carho, are peculiar -;

to the Old World,

and

three, americana, perspicillataand deglandi are found in the

New,

where along our Atlantic coast they are popularly

known

to

many

ofour gunners_as"Coots."

Historicallyconsidered the Scoters are ofrespectable antiquity, fortheveryearly writersonbirdshave

had

somethingtosayabout them. In 1555, Belon (L'Hist. Nat. Oyseaux) seems to refer toa sea-duck,

and

in 1560, Gesner (Icon. Animal., p. 76) mentions

"Ajias ferafusca" but atbest fourteenth century descriptions are too vague

and

imperfect to

make much

out of them. In _1634, however, Aldrovand^(Ornith., iii, p. 234) not only describes the ] I

common European

speciesfusca under the title "

De

anate nigra, rostro nigro, rubro

&

luteo" but also inserts a strange-looking wood-cut of the

duck

with the white wing

band

and e^e-crescent

293

294

DwiGHT, Plumages _of the Scoters. [july

most

conspicuous. In 1650-1653, Jonston (Nat. Hist.

Avium,

p. 98) mentionsthisbirdwhich he figureson plate49 with awhite wingband, callingit "

Anas

fusca

f

^era,"butthefirstauthorrecog- nizingtwo species seemsto

have

beenWillughby (Ornithol. 1676).

At

p. 363heproposes the

name "Velvet-Duck"

for "Aldrovandus hisblack

Duck,"

reproducingthelatter'swood-cuton plate

LXX,

and calling the bird

"Anas

niger major."

He

describes a second species at p. 280 whichhe calls"

Anas

nigerminor," figuringiton plate

LXXIV, and

this is evidently

what

is

known

as7iigratoday.

In 1713,

Ray

(Synop.

Avium,

p. 141) describes

"Anas

niger" (

=

fusca) and

"Anas

niger

minor" (=

nigra)

and

in 1746 Linnaeus (FaunaSuecica, p. 38, Nos. 106, 107) describes ^"

Anas

fusca"

and what

seemstobe an

immature

nigra,butlike

most

ofthe old writers

much

is

made

of the unimportant characters whichare shared

by many

^birds,

and

thereal differences are completely missed. This

failing, however, I

am

sorryto say is not confined entirely to the pioneers in ornithology.

In 1750,

Edwards

(Nat. Hist. Birds, iii, p. 155) describes the

"Great Black

Duck

from Hudson's

Bay"

whichhiscolored plate

—

thefirstof

any

Scoter

—

showsisloerspiciUata,

and

in1758Linnfeus (Syst. Nat. ^i, pp. 123

and

125) gives the

names "Anas

fusca,"

"Anas

nigra"

and "Anas

perspicillata" to the three species that retain his specific

names

to this day. In 1760, Brisson (Ornithol- ogie, vi, pp. 420-427) describes at considerable length the three speciesas

"Anas

nigra"

(=

nigra),

"Anas

nigramajor"

(=

fusca)

and "Anas

nigramajorFretiHudsonis"

(=

perspicillata)

and many

later writers might be cited. It

would

be out of place to review their statements in this brief sketch for a

volume

could be filled correcting

and

explaining the

many

blunders thathave been made.

My

^{chiefobjectisrathertoclear}

up

suchobscurityasstillremains.

It

may

beof interest,however, tocallattentiontothefactthat the

two American

species ofScoterswerelong confused,americanawith the

European

nigra

and

deglandiwithfusca,

and

notuntil1831 did Swainson

and

Richardson (Faun. Bor. Amer., ii, p. 450) recognize americana as distinct, while it

was

1850

when

Bonaparte (Rev.

Crit. Orn. Europe, p. 108) separated deglandi. Finally, carho

was

recognized as a full species in 1887

by Ridgway

(Man. N.

Am.

Birds,p.112)underthe

name

stejnegeri. Thereare thereforeinall

•°j,jj*4 "

J DwiGHT, Plumages of ^the Scoters.

295

sixspecies in thegenus Oidemia, theheadsofwhich (Plate

XXIV)

have been

drawn

and colored true to life

and

in

most

cases from fresh birds

by Mr. Henry

Thurston.

The

featheringof thebills is

diagnosticofeachinallplumages.

The

questionofgenera need not detain uslong. I

am

not one

who

believes in

making

generic distinctions so fine that nothing

is left except monotypic groups

and

it seems to

me

that there should be

some

differencebetween a genus

and

a species. Unless

we

recognize the six species

now

in Oidemia as congeneric, there should be six genera. Fleming (Philos. of Zool., ii, p. 260, 1822) establishedthegenusOidemia (laterspelled CEdemia)

and

although

five other genera have since then

had more

or less vogue, there seemsno goodreasonforrecognizing

any

ofthem.

Inviewofall thathasbeenwrittenaboutthe Scotersduringthe

many

years thattheyhave been

known

to ornithologists, it

would seem

superfluous to

add

to a literature that alreadyseems replete were it not that very little has been published bearing directly

upon

the moultitself and the

way

that it isrelated to plumages.

Over

a dozen years ago I took

up

the study of the moult of the Scoters

making

use ofspecimens thatwerefreshly killed. In this

way

it has been possible for

me

to follow the

plumage

changes

much more

accuratelythan merely with dried skins

and now

with thelarge seriesat

hand

thatwerefirstso studied, I

am

preparedto

show some new

facts

and

correlate a good

many

others that have been imperfectly understood.

My own

^collection includes the following specimens, viz. Oidemia am,ericana, 18 adult males, 6 adult females, 10

young

males

and

3

young

females; 0. perspicil- lata, 23adult males, 6 adult females, 21

yoimg

males

and

10

young

females; 0. deglandi,23adult males, 9 adult females, 10

young

males and 22 adult females; 0. carbo, 2 adult males; 0. fusca, 3 adult males; and 0. nigra, 3 adult males, 1

young

female,and 1

downy

young.

The

bulk of

my

specimens

came

from

Long

Island,

New

York, but besides

my own

birds I

have

examined fully as

many

others in other private and public collections kindly placed at

my

disposal.

As

a consequence I have

had no

dearth of material exceptperhaps ofbreedingbirds,

and have

been able topieceout very complete series of

most

^{of the species,} representing every

month

in theyear.

296

DwiGHT, Plumages of the Scoters.

[jiily

The

question issometimes asked^:

How may

theageof ducks be determined? There are several

ways

of approximating this in wild birds. Ofcourse

young

birds

show

several skeletalcharacters thatpersist for

many

months, butthe

plumage —

onceit is

known

—

givesus theclue that laststhelongest. It issingularthatnone of our

American

authorities since Nuttall in 1834 has ever

made

mention of the important emarginate first, or distal primary of adultmalesofamericana, norhaveforeign writerson themoult of nigrarecognized its value.

The

likefeatherin

young

birds of this species is of quite adifferent shape, afact of importance because, until a bird isa yearold, the primary

marks him

asa

young

bird no matter

what

sort of

plumage

he

may

assume.

For

^{the reason} that neither this nor the other primaries in ducks are moulted

more

than once in ayear thisonefeatherisakeytothe

many

so called

"immature"

plumages. I haveillustrated(Plate

XXV)

the differencesbetween the tapering feather tip in

young

males ^(Figs.

1-4)

and

the cut or emarginate tip in adults (Figs. 5-8).

The same

condition prevails in the

European

speciesiiigraas

shown by

Plate

XXVI

(Figs. 1

and

5) where, for comparison, I have also placed maleperspicillata (Figs. 2

and

6), deglandi (Figs. 3

and

7),

and

fusca (Figs. 4

and

8)

young and

old. Ihavealso addedPlate

XXVII making

a similar comparison between

young and

adult femalesofamericana (Figs. 1 and_5),deglandi (Figs.2 and_Q),fusca (Figs. 3 and 7)

and

'perspicillata (Figs. 4

and

8). This method, whichconsists of holding the feather overblue-print paper, might becalledanavianBertillonsystem with

wing

tipsinsteadof fingers for identification, andI feelconfident thatit

may

hold

some

future possibilities. While a great variation is here

shown by

the

wing

prints itshould be noted that even where the differences between the

young and

the adult bird overlap, there is a tendency for the adultsofthe Scoterstohavelarger,widerfeathers,withtheexcep- tion of americana and nigra which alone have the singular cut or emarginateprimary in the adult.

As

^themoultsofallthe Scotersofthe

New

World,

and

probably thoseoftheOldarethe

same and

the sequenceofplumagesidenti- cal, a better understanding of

them may

be obtained

by

taking

them up

innatural sequence.

The

growthof

new

feathers always begins atdefinite points, justasitdoesinotherbirds,

and

^extends

The

Auk, ^Vol.

XXXI

^Plate

^XXV.

Distal Primaries of Oidemia ^americana.

Youngmales, Figs. 1-4. Adult males.^{Figs. 5-8.}

The

Auk, Vol.

XXXI.

_Plate

XXVI.

Distal Primarie.s of Males.

Oidemianigra, young male, Fig. 1

The

Auk, ^Vol.

XXXI.

^{Pl.^te}

XXVI

^1.

Distal Primaries of Femalec Oidemia ^americana, young female, Fig. 1

deglandi, Jusca,

perspicillata,

Fig. 2 Fig. 3 Fig. 4

adult, Fig. 5.

Fig. ^6.

Fig. 7.

Fig. S.

^°\914^T

^{DwiGHT, Plumages of the Scoters.}

297

along^definite paths. Thisshows clearly inthe Scoters where the black feathers oftheheadbeginto

show

chiefly anteriorly

and

the moult

moves

slowly backward, leaving a gap on the neck before

itjoins the spoton the breast

and

backwherea similar

backward movement

has been in progress (Plate

XXVIII,

Fig. 2;

XXIX,

Fig. 2; and

XXX,

Fig. 2). Feather growth next extends along thesides

and

flanks andthelast area to be affected

by

a moult is

the middle part of the

abdomen

(Plate

XXVIII,

Fig. 3;

XXIX,

Fig.3;

and XXX,

Fig. 3), although in the

downy

chick thisarea

isclothed before thewing-quills sprout.

There

is no haphazard growth.

Moult may

be delayed, espe- cially in females, orit

may

be checked ⁱⁿ

some young

birds before

ithas extendedas far asitdoesin others,butbirds ofthe

same

age have approximatelythe

same

plumages.

The

difficultyhasalways beento classifyplumages

and

moults

by

name,

and

thisisparticu- larlydifficultin the Scotersbecause thereis

no month

inthewhole year

when some

individuals

may

not be found moulting. Espe-

ciallyisthistrueof

young

birdsarriving

from

thenorthernbreeding grounds, in full juvenal plumage,

some

showing the growth of a fewwinter

plumage

feathers inOctoberandothers beingnofarther advancedin

March.

Furthermore

some

males

have become

largely black

by

January while others are at a similar stage in April, so that

young

birds

may

be found in active moult throughout the entirewinter. Specimensexamined

when

freshly-killed

show many

pin feathers thateasily escape notice in skins

and

I

am

convinced that there are

two

moults concerned in the changes of the first

winter, a partial postjuvenal

and

a partial prenuptial.

Both

produce black feathers in themale

and brown

onesin the female, but where oneleavesoffandtheother beginsit isimpossibleto say.

As we

find

new

black feathers

among

old black ones

we may

as-

sume

such birdshave undergone

two

moults,butasarule

we

find

new

black

among browm

feathers only which indicates the post- juvenalmoult

and

thegrowthoffirstwinterfeathers.

When

such growth occurs in spring birds

however

it seems rather absurd to call

them

firstwinterfeathersratherthan^firstnuptial,but

we must

either do this, consider the first winter

plumage

suppressed in

some

individuals,or consider the postjuvenalmoultasaborted

and

its placetaken

by

the prenuptial. Itismerelya questionof

what

\

298

DwiGHT, Plumages _of the Scoters. [july

is the best

way

of expressingfacts andas the stages of moult

and

of

phimage

overlap

and

it is simplest to

draw

an arbitrary line somewhere.

During

the first winter, the knobs

and

bulgings of the bills of males gradually appear as well as the colors that are peculiar to

them and

tothelegsandfeet.

The

iris,

brown

inallfemales,inall

young

birdsofbothsexes

and

inthe adultsofamericanaandnigra, in males becomes paleyellowduringthewinter

and by

the endof the year white in dcglandi, carbo,

fmca

^and perspicillata. After the complete first postnuptial moult in August,

young

birds are scarcely distinguishable

from

adults, althoughin

some

the

plumage

is not so black

and

the bills are less bulged.

From now

on adults,both male

and

female,notonly

have

a completepostnuptial moult eachAugust or September,

when

through simultaneous loss of all the wing-quills, they lose the

power

of flight, but they also undergo a partial prenuptial moult in ]\Iarch and April which involves the

body plumage and

the tail, never the remiges of the wings. Ihaveyet toseeanadult birdof

any

of the speciestaken in the spring w^hich is not in active moult,

and

that this stage of moult should have been completely overlooked ^is a matter that

may

well surpriseus. I

do

notfindevidenceof

any

eclipse

plumage

in the Scoters as is claimed

by

a recent writer, a point to be dis- cussed later.

With

thesepreliminary remarksvrhich apply indis- criminately to

any

of the Scoters,

we may

take

up

each species inturn

and show

the development ofits plumages and moults. I cite

by number

only such specimens as

seem worthy

of special noticeinordertofixa

day

ortoemphasizeafact.

Oidemia americana.

Natal Doicn.

The

only specimen examined

(Am. Mus. No.

76845, Gichiga,X.E.Siberia,Aug.17)isoneabouthalf

grown

and

it already has acquired

some

of the juvenal plumage.

The

bird seems to be indistinguishable

from

a younger specimen of nigra

(J. D., Jr. Xo. 30919, July 30)

from Xorway.

It is dark

brown

above

and

^lighter below,

an

indistinct collarseparating the breast

from

the stillwhiterchin

and

throat; a dark bro"«'n cap isindis- tinctly outlined foreshadowing that of the next plumage.

The

^

^

'^^^ioif'^''] DwiGHT, Plumages _of the Scoters.

299

wing-quills are just showing with the

down

still adherentat their apices.

The

tailis

grown and much worn

illustratingthefactthat in the duck, a water fowl, the tail develops earlier than

do

the flightfeatherswhichiscontrarytothe orderofmoultinlandbirds.

The

scapulars

and

breast feathers are partlygro\\Ti.

Juvenal

Plumage

(Plate

XXVIII,

Fig. 1), acquired

by

a

com-

pletepost natal moult,andinthisdress the sexesarealikealthough females average a little smaller in

most

of their measurements.

Itis unsafe withoutdissection to attemptto distinguish thesexes untilfeathers ofthefirstwinter

plumage

begin toappeartogether withthelaterchangesinthecolor

and

formofthebillinthemale.

Young

males arriving

from

the north in October (J. D., Jr., No.

9798, Oct. 26)

and

inearly

November

(J.D.,Jr.,No.4716,

Nov.

8) soon begin to

show

a scatteredgrowthofblack feathers

and

later the females

show brown

feathersbutthe juvenaldress

may

be

worn

in

some

cases forseveral

months

before the postjuvenalmoultsets in.

A

spring female (J. D., Jr., No. 4867,

March

4), forexample,

is wholly in juvenal

plumage

with merely a few

new

feathers be- gining toappear. 0. nigra

and

americana are practically alike in thisplumage,being

brown

above withadark cap

and

lighterbelow, but the bill of 7iigra is rather heavier; deglandi, carho,fusca and perspicillata are

brown

above, lighter below

and show

two large whitespots on thesideofthe head,

and

deglandi, carho,andfusca have white wingpatches.

1stWinter

Plumage

(Plate

XXVIII,

Figs.2

and

3), acquired

by a

partial postjuvenal moult which never includes the wings

and

seldom the lower surface of the body.

At most

the head, neck, back and sides

become

black in males

and

a

much

less extensive growth of

brown

feathers occurring relatively later takes place in females.

The

tail too is moulted, therectricesshowingirregulari- ties in their replacement.

The

moult probably progresses slowly butit

must

be

remembered

thatinthewinter while

we

see individ- uals in all stages no doubt theybegintomoultat widelydifferent dates and it is impossible to say just

how

long

any

one bird has beenactuallymoulting. I

am

convincedthatmales whichare well advanced

by

January, also undergo a prenuptial moult in April or

May,

likeadults, butitis difficulttotellwhetherthespecimens which are moulting at this late period are undergoing a

much

/

300

^{DwiGHT, Plumages} of ^the Scoters. [july

delayed postjuvenal or a distinct prenuptial moult.

The

results are the

same

so far as the

plumage

is concerned,the

new

feathers being blackineachcase, but, iftherebea prenuptial moult, three differentgenerations of feathers can befoundwhileas a rule only

two

are demonstrable.

The most

developed specimen I haveseen

(J.D.,Jr., No.4412,0^, April20),isalmost whollyblack except the wings

and

a fewscattered

brown

feathersonthe

abdomen

andthe back,but

we

^{have no}

means

of

knowing how many

birdsreachthis advanced stage

—

probably very few.

The abdomen,

as a rule,

becomes

darker anteriorly

and

posteriorly as the feather edgings arenarrowerhere

and

sooner

show

thedarkbasalpartasthey

wear

offandthe fadingisconsiderable.

Shortly after

new

feathers appear, the bill of the

young

male begins to take on the colors of the adultand still

more

gradually assumes its shape.

The

colors

may

closely approximate,

by

the endofthe winter, thoseoftheadult,buttheshapeisnotperfected foratleastayear, the swellingofthe

hump

notbeing

marked

ⁱⁿthe first winterbirdsalthough theyellowcolor

may

be brilliant.

The

bill of the femaleand the legsand feet of themale remaindusky, adultsdifferingvery^little

from young

birds.

No

matter

how

black the

plumage

^{maj^} be nor

how

bright the colors of^billorfeet,

young

males

may

infalliblybetoldfromadults

by

theshapeofthefirstprimary(Plate

XXV)

whichisnotreplaced until the firstpostnuptial moult.

The

iris in americana is always

brown

ⁱⁿ bothsexes atallages.

1stNuptial Plumage. Thisiseitherthefirstwinter

plumage

plus

more

orlesswear, being therefore amixtureof

much worn

juvenal

and

less

worn

firstwinterfeathers, orit is,in part, the result of a

firstprenuptialmoult. It is prettywellestablished

from

observa- tions on birds in captivity that no ducks breed until their second year.

2d Winter Plumage, acquired

by

a complete first postnuptial moult. Itis probable thatthis moultbeginsinJuly,buta lackof specimens prevents

me

from giving exact dates.

A

specimen of Dr. L. B. Bishop's (No. 557,

August

28) isa male thathasnearly completedthismoult

and

acquired theemarginateprimary. There are enough

worn brown

juvenal feathers remaining to

show

that the bird never

had assumed much

^{of the first}winter dress.

As

a

Vol.

XXXIl

1914 ] DwiGHT, Plumages _of the Scoters.

301

rulethe moultis almost completed

when

the birds reach ourlati- tude.

At

this time the characteristic emarginate distal primary

is

assumed

replacing the uncut juvenal feather (Plate

XXV)

and

the yellow

hump

of the bill has in

some

cases reached full

development.

The plumage

is

now

wholly black.

As

early as October 26 (J. D., Jr., No. 9796) I

have

seen a specimenthat

had

ceasedto

show any

signs ofmoultwhile othersas late as

November

12 (J. D., Jr., No. 11983) still

show

a fewpin feathersgrowing on several ofthe feathertracts. Thereisadifference intheintensity ofthe blackinfallspecimens

and we may

supposethe blackest are birds several years old although it is probable that individual variationisthereal factor.

At

^all events,the duller birdsarethe ones that in the course of the winter

show

the

most wear and become more

orless

brown

inthesecondspring. It

may

benoted that the growth of the

hump

of the bill tilts the nostrilfrom the

more

horizontal position it has in the

young

male.

The

nostrils of dcglandi

and

perspiciUata being wholly within the zone of the upliftdo notlose their relative positions.

Sd Nuptial

Plumage

(and ^alllaternuptialplumages) acquired

by

apartialprenuptialmoultinvolving the

body

feathersandthetail.

Contrary togeneral opinionan extensive moulttakes place at this period in bothsexes.

No

birds of

many

examined in

March

and April fail to

show abundant

growth of

new

feathers.

As

these, however,areblacklike theoldones theyreplace, no changeinthe appearance of birds is affected save that the plumages look fresh

and

new.

3d Winter plumage(andalllaterwinterplumages) (Plate

XXVIII,

Fig. 4, cf; Fig. 5, 9^{) acquired}

by

a complete second postnuptial moult. Differs onlyfrom the first postnuptial

plumage

in that a blackemarginateprimaryreplacesasimilaroneinstead ofreplacing aplain

brown

juvenal featherasat the first postnuptial moult.

A

largepartofthe variationinintensity of colorinplumage, ^billsand feet isprobablyin consequence^of

some

adults being only oneyear old while others are

two

or more.

The

adult female is uniformly dark

brown

above

and

below, whereasthe juvenal female is

much

lighterbelow and shows a

more

distinct cap.

302

DwiGHT, Plumages _of the Scoters.

IJuly

Oidemia

perspicillata.

NatalDoicn. I

know

^ofno specimen in collections.

Jvvenal

Plumage

(Plate

XXIX,

Fig. 1) acquired

by

a complete postnatalmoult. Femalesarea littlesmaller, butin

plumage

the sexes are alike, the color being browTi"«-ith

two

conspicuouswhite patches or rounded spots on the side of thehead. These vary in size, sometimesnearlymerging; the anterioriswhiterandsmaller, and theposterior isalso smallerthan in deglandi

and

they tendto

become

whiter with

wear and

fading.

The

absence of white on the

wing

separates this species

from

deglandi, carbo

and

fusca

and

the feathering of the bill is, of course, diagnostic. Birds in this

plumage much worn may

be found late in thewinterbutasa rule thegrowthof thefirstwinter dress begins in Octoberratherearlier than in americana.

1stWiriterPlumage. (Plate

XXIX,

Figs.2

and

3) acquired

by

a partial postjuvenal moultthe extent ofwhich is variable.

A

few blackfeathersat the cornersofthemouth, along themarginofthe

bill,

and

on the interramal space

may

begin to

show by

early October (J. D., Jr., No.34151, cf,Oct. 2).

I have

some

specimens that are as far advanced in

December

(J. D., Jr., No. 8045 cf, Dec.6) as others arein

March

(J. D.,Jr.,

No. 7419 d^, INIarch 17) or evenApril, suchbirdshaving the head, neck, fore-part of the body, the sides, scapular region

and rump

black

and

a single white nuchal patch. Females are

more

back-

ward and more

limited in their moult

and

the

new

feathers are

brown

insteadofblack.

The

tailisrenewed duringthefirst•n-inter

and colors

come

gradually into the bill

and

feet of males.

The

change in the shape ofthe bill is slower, a wrinkling ofthe black bosses being theearliest sign, but the winter has gonebefore bills

andfeetcan bemistakenforthose oftheadult.

The

iris is

brown

in

young

males, becoming yellow and finally white

when

the bird

isabout ayearold.

It is of interest that

young

males acquire only the posterioror nuchal, ofthetwotriangularwhiteareasthat

mark

thehead ofthe adult.

The

area where the frontal patch is developed ⁱⁿ the old maleiscovered

by

black feathersinthe

yoimg

bird.

The two

juve-

^

a

°i5r4 J DwiGHT, Plumages of ^the Scoters.

303

nalwhite spotson the side of thehead are completelyobliterated

by

^blackfeathers as the postjuvenalmoultprogressesandthefresh white nuchalpatch becomes

more

or lessprominent varying indi- vidually greatlyinextentandpurityofcolor.

1st Nuptial Plumage. Practically the

same

as the first winter with

wear

added which creates greater havoc

among

the

brown

juyenal, than

among

the black first winter feathers. In

some

birds,perhaps

many,

there is a prenuptial moultwhich adds black feathers to those already

grown

orreplaces them. Yearling birds do notbreed

and

arelate inbeginning the postnuptial moult.

A

specimen (J. D., Jr., No. 4367) taken September 4well illustrates

wear

as well as the delayed postnuptialmoult in

immature

^birds,

forthe

brown

feathers ofwings, tail, lower partsand backare the

worn and

faded juvenal feathers, the black ones of head, neck, breast, andsides areoffirstwinter (or perhapsfirstnuptial) while here

and

there afewblack feathersofthesecond winter

plumage

are justbeginningtoappear. Itmightwell be

November

beforesuch a bird as this

would

complete his moult.

Ifind

no

evidenceof an ^"eclipse"

plumage

asisclaimedbut can understand

how

retained

brown

and

worn

feathers of an earlier

plumage

couldbemistakenforan ^"eclipse"growth.

2d Winter Pluviage, acquired

by

a complete first postnuptial moult, atwhichtheadult

plumage

isassumed.

The

male

now

has

two

white triangles on the head and the colored bulging bill,

and

thefemaleassumesa

plumage much

darkerthaninthefirstwinter.

Shelosesto alarge extent the

two

juvenalwhite spotson theside of the head for which are substituted an obscure anterior and a

more

conspicuousposteriorwhitish spot, bothof

them

obscured

by

the

dusky

feather tips which later are

worn

^off.

The

female too hasanindistinctcapwhichisblackerthanindeglandiandshe

may

or

may

not have an indistinct white nuchal patch similar to the male,

—

the individual variationisconsiderable.

2d Nuptial

Plumage

(and all later nuptial plumages) acquired partly

by

wear, mostly

by

a partial prenuptial moult confined chiefly tothehead andsides.

Many

birdsexaminedin

March

and April

show

the growth of

new

black feathers

among

the old.

A

specimen (Amer.

Mus.

No. 102082) of

May

19 still shows

new

growth giving the

abdomen

amottledlook andthesides ablacker tint.

304

DwiGHT, Plumages _of the Scoters. [july

Sd Winter

Plumage

(and all later winter plumages) (Plate

XXIX,

Fig. 4 cf^, Fig. 5

9)

^acquired

by

acomplete second post- nuptial moult.

A

specimen

(Am. Mus.

No. 90694 cf, July 28) has moultedthe

body

plumage, butstillretainsthewings

and

tail,

another

(Am. Mus.

No. 119177cf,Aug.4)isataboutthe

same

stage

and

still another (No. 7151 cf, Sept. 1) is at the flightless stage having shedthe

wing

quills. Stillanother(Am.

Mus.

No. 76208 d^

,

Aug.24) isthe

most

advanced

and

has

new

flight-feathers, tail

and body

feathers mostly grown.

The

less highlydeveloped bills and the browner

plumage

of

some

birds

may

or

may

not indicate less

mature

birds, but on accountofindividual variationit isimpossible to guess the age ofsuch specimens with

any

certainty, after they losethelastofthejuvenalfeathers.

We must know

theageofthe feathersif

we

wishto

know

theageofthebird.

Oidemia

deglandi.

Natal

Down. Dusky brown

above

and

dullwhitebelow,whitish under the eye andawhite patchof

down

foreshadowing thewhite

wing

patch.

Juvenal

Plumage

(Plate

XXX,

Fig. 1) acquired

by

a complete postnatal moult.

The

white speculum distinguishes this species fromallthe Scoters except fuscaandcarhowhichitcloselyresembles in this plumage.

The

light patches on the sides of the head are asa ruleratherlarger thanthose of yerspicillata

and

are often ofa dingierwhite.

The

posteriorspot isthelarger of thetwo and the anterior is apt to be brownish towards the bill. There is

much

variation, thelightarea oftenextending tothe foreheadand some- timesalmostcoalescingwiththe posteriorspot.

The

featheringof thebill isdiagnostic. Birdswhollyin this

plumage may

be found

from

October (J. D., Jr., No. 474, 9, Oct. 21) to April (J. D., Jr.,

No. 34134 9, ^April 18).

1st Winter

Plumage

(Plate

XXX,

Figs. 2 and 3) acquired

by

a partial postjuvenal moult,

more

orlessofthe

brown body plumage

being replaced

by

black feathersin the male,

brown

inthe female;

the white head patches are obliterated in themale,merely dulled in the female.

A band

of dark

brown

feathers develops in males along the sides

and

flanks, but it is less conspicuous than in the

^

X X

^°'i9i4''^^] DwiGHT, Plumages of ^the Scoters.

305

adult.

The

color of the bill soon approximates ^{that of the adult} but the

upward

swelling of the culmen seemsto requireayear or

more

for its full development, as indicated

by

specimens that are adultinplumage.

The

whiteofthe secondariesisnotsoextensive asit isin adults,butthisisa variablecharacter.

It is

worthy

^{of careful} note that

no

white crescent below and behind the eye develops ^until the first postnuptial moult.

The

little feathers of the lower eyelid,

brown

ⁱⁿ the other species, in this one aredingy whiteⁱⁿ the juvenaldress

and

fade whiter, and

when

the

new

feathers of the first winter

grow

they are either a dingy whiteor

more

often tippedwith

brown

or blackwhichis lost as the tips

wear

^off, but no white feathers

grow

during the first

winter onthe area

where

thewhite crescentof the adultisfound.

1st Nuptial Plumage. Practically the

same

as the first winter plus

wear

orwithapartialprenuptialmoultandtherefore chieflya mixture of juvenal and firstwinter ^feathers,

and

sometimes those added

by

the prenuptial moult.

2d Winter

Plumage

acquired

by

a complete postnuptial moult.

Adultcharacters are

now assumed

except that the billhasless ofa

"hump"

thaninolderbirds,butthere isdoubtless great individual variation.

The brown band

along the sides is

now

conspicuous and wears

and

fades because of its color

more

than do the black feathers ofadjacentparts. In fuscaandcarbo,however,this

band

is as black as the breastand

abdomen

adjacent.

A

bird belated in moult (Am.

Mus.

No. 115554, September 17), has

new

wings

and

^tail, but stillretains

brown

juvenalfeathersbelow and on the back, while about the head and elsewhere are scattered

many brown

greatly

worn

feathers; thewhitespotbelowthe eyeissmall, thebill isslopingbutitscolorisbright.

In the adult female the obliteration of the white spots of the side of the head is

much more

complete than in perspicillata

and

the feathers that

grow upon them

are basally whiter

and

often merelytippedwithblackespeciallythoseoftheposterior spot.

2d Nuptial

Plumage

acquired

by

a partial prenuptial moult as

shown by many

specimens moulting ^{in April}

and May. As

this

plumage

is the

same

as the winter the only obvious ^{effect is to} freshen

up

thebird.

A

specimen(J.D.,Jr., No. 8238d") of

May

⁸

shows the

brown band much worn

with the darker

new brown

306

DwiGHT, Plumages ofthe Scoters. [j^y

feathers coming in, while elsewhere black are replacing black

and

arenotobvious unless studiedinthefresh bird.

A

similarspecimen

was

taken

May

20 (J. D., Jr., No. 8242)

and

^I have seen several others. Still another (J. D., Jr., No. 29981) of June 26 shows

much wear

and fading especially on the wing-quills where the patternofeach overlapping primaryisimpressed onthe protected featherbeneath.

As

this bird

was

perhapscrippled

and

certainly w^as one that

had

not gone north in migration, the late date of feathergrowth

may

thusbeexplained.

3d Winter

Plumage

(and alllaterwinterplumages) (Plate

XXX,

Fig. 4, cf, Fig. 5,

9)

^acquired

by

a complete second postnuptial moult. Birds are

now

fullyadult.

Males

witha

knob

ontheirbillsareprobably a year

and

^ahalfold atleast

and

thosewiththe biggestknobs

two

years old ormore.

The

variationin size

and

in colorisveryconsiderable, partofit

being due to age

and

part of it being individual.

The

depth of color in theplumage, thesize of the eye-crescent

and

ofthewhite area on thewings is also variable.

Adult females are quite sooty

and

ⁱⁿ fresh

plumage

are devoid ofwhiteaboutthehead butasthefeather-tips

wear

away, exposing thewhite basal portionsofthe feathers

more

orlessdistinctwhite patchesappear

on

thesides ofthehead, especiallyover thesiteof theposterior juvenalspot.

The wear

is

most marked

in breeding specimens. Females do not assume bills with knobs, nor are the billscoloredexcepta

band

nearthenail.

Oidemia

carbo.

The

plumages

and

moults of this species

seem

to correspond to thoseof 0. deglandiwhichit

most

resembles, butIhaveseen only eight specimens all told. Itdiffers

from

deglandiin a bill witha concave

knob

that suggests a battle-ship so

marked

is the over- hanging protuberance, the loral feathering extending farther for-

ward

than thefrontal,

and

thelatter roundedor flattened instead of extending into an angle. Besides this it is very large and the adultmale has black flanks

and

sides, instead of

brown

as in deg- landi, a character which it shares withfusca.

The

feathering of the billseems tobe diagnostic (Plate

XXIV,

Fig. 6), andits color seems tobe richerthan in deglandi.

Vol.

XXXIl

1914^ _J DwiGHT, Plumages of the Scoters.

307

Oidemia

nigra

and Oidemia

fusca.

It

would

befollyfor

me

withthe limited materialIhave examined to attempt to follow, as I have done with the three

American

species, themoults and plumagesofthese foreign species, butfor- tunately

we may

turn for this to J. G. Millais' "British Diving Ducks," 1913. In this splendid

work

will be found the best accounts yet publishedofthemoultingofcertainducks

and

Iagree with almost all of the views expressed therein regarding Scoters.

Still,Iregard theterm

"immature"

astoovaguetocover thesitua- tion satisfactorih'and I findno mentionis

made

^oftheprenuptial moultof adults, noroftheemarginate primaryof nigra, while the occurrence of an "eclipse" is claimed for nigra,fusca and even

perspicillata. 1 will quote

Mr.

Millias'

own

words regarding the

"eclipse" in the Velvet-Scoter (fusca).

"Themost interesting feature, however, is a patch of whitish brown echpsefeathersbehindtheeyeandthebillwhichhadevidentlycomein in Julyandgivethe bird a female appearance. Infront ofthesefeathersisa jetblackpatchwhichhas,however, onlybeen renewedonceintheplumage change (July-November). Thebreastandlower partsarebrownand^the

tailand wings arebeingrenewed. Thebirdwasincapable offlight when

Ishot it."

His photographicplate ofthe birdshows a dorsal view withthe head turned toone side

and

without actuallyhavingthespecimen in

hand

I

must

say that the "eclipse" feathers look suspiciously like

worn

feathers of an earlier

plumage

and probably were ac- quired at the prenuptial moult.

Such

feathers frequently persist

on

these (and other) areas

and

I havea specimen of the closely related dcglandi

(Am. Mus.

No. 119176 cf ad., June2,

Mackenzie

River delta) which matches the one in question verynearly,

new

black,growing

among

thebrownish feathersnearthe bill. I con- sider

my

bird as beginning the postnuptial moult, for the flight feathers

and

^tailareold

and

therearecomparatively fewevidences of moult elsewhere. Specimens of perspicillata

and

americana

show

no signswhateverof "eclipse"inJuly, AugustorSeptember, although

some

birds are browner than others about the head, whichismerelyindividual variation.

The

feathersof perspicillata

308

DwiGHT, Plumages oj the Scoters. [july

and

deglandi on an average are whiter basally than are those of nigra,fusca

and

americana.

I find adult specimens showing the prenuptial moult both in nigra

and

fusca.

An

adult ofnigra (J. D., Jr., No. 14233 <^ ad.

mid-March, near Liibeck) shows

new

growth well advanced

and

anothernigra

(Am.

Mus., No. 26S93 cf ad.,

May

18, Havre) still

shows growth of

new

black feathers

among

rusty old black ones.

An

adult specimen offusca (J. D., Jr., No. 24553 cf ad.,

May

5,

Norway)

showschieflyrusty black featherswith

new

ones growing, while in another bird (J. D., Jr., 14234 cf ad., June 8,

Norway)

the growth seems to

have

ceased. It will be observed that the prenuptial moult in

American

Scoters runs over in point of time almost ^if not quite into the postnuptial

and

I really do not see w^here an "eclipse" could

come

in, but I do see

how

"whitish

brown"

feathers

may

well be found behind a fresh patch of "jet black" without invokingthe aidofan^"eclipse."

It is evident that

Mr.

Millais is in

some

doubt about itfor he pensthe followingregardingan "eclipse "innigra, viz.:

"The principal moult towards maturity commences in July when the birdisoneyearold.

A

numberoftemporarybrownfeathers, which

may

be called the firsteclipse appearon thehead and neck thesebeing again shedin lateOctober."....

"Likeallthe Scoters the local

common

Scoterhasonly a shght eclipse plumage if it

may

be so called. At the end of July a few dull brown feathersappearonthe cheeksandneck. Belowtheloresand onthe throat

many

ofthese feathersare ofadirtywhitecoloranditgivestheoldmalea certain resemblance toa female and for which they have doubtlessbeen mistaken.

No

author that I can discover mentions having seen this eclipseplumage whichisretainedto late intheautumnbutIhaveexamined twomaleskilled inAugustinIcelandwhichexliibittliisdress."

Itseems to

me

that the facts have been observed correctlybut interpreted wrongly.

As

I have stated before, the Scoters are moulting practically throughout the whole year

and

to say

where

onemoultbeginsand another endsis notaneasy matter. I

have

endeavoredto

show when

certaincharactersof

plumage

areacquired

and

that thedefinitesequenceinfeathergrowthfurnishes a

key

to theage of specimens. Unless the ageof specimens can be deter-

mined

verylittleprogress ispossible insettlingquestionsof

moult

and

plumage.